1. Field of the Invention
This invention relates to the acid delinting of cottonseed and is more particularly concerned with a product for and process of delinting cottonseed.
2. Description of the Prior Art
Cottonseeds, which are the by-product of a cotton ginning operation, are covered with fibrous lint attached to the seeds. This lint causes an agglomeration or clustering of the seeds and prevents the ready mechanical handling of individual seeds in producing oil and meal therefrom, in grading handling and storing the seeds and in mechanically planting the seeds. Thus, two general methods have been developed for removing the lint from the seed. One such process mechanically removes the lint, while the other such process chemically removes the lint.
The mechanical delinting of the cottonseed is usually accomplished by an apparatus employing high speed sharp saws or abrasive surfaces which cut or rub the fibers off of the hull. The advantages of this type of operation is that the fibers are not degraded during the operation and can be sold for various purposes. Also, since the seeds are to be subsequently crushed for oil or meal, the damage sustained by the seeds is not detrimental to their further use. The disadvantages of the mechanical delinting operation is that it requires substantial amounts of power, the maintenance costs are high and the damage caused to the seeds may preclude the use of such seeds for planting purposes. Of primary importance is the fact that under current government regulations in the United States, namely the Cotton Dust Control Standards Act, such plants which mechanically delint may not be able to continue to operate without very material alterations to their quite expensive equipment. U.S. Pat. No. 672,297 typifies the mechanical delinting machinery.
The acid delinting of cottonseed has been extensively used, particularly when the seeds are to be employed for planting purposes. Both sulfuric acid and hydrochloric acid have been respectively used for such acid delinting. In concentrated form however, hydrochloric acid is a gas and has been used for delinting cottonseed. Usually heat is employed to accelerate the chemical reaction and the acid is neutralized with anhydrous ammonia.
The hydrochloric acid method is currently used only in areas where ambient humidity levels are very low. Furthermore, there is a danger of killing the seeds with excess hydrochloric acid and there is the objectionable smell of the ammonia and the corrosion caused by the vapors of hydrochloric acid. Here again, material alterations to the process may be required in order to comply with current clean air standards.
The most accepted procedure for the delinting of cottonseed is the utilization of dilute sulfuric acid which is comingled with the cottonseed. After the delinting operation, the seeds are washed then dried with heat.
In some processes, the seeds are prewet and then the concentrated sulfuric acid added to the mixture of water and cottonseed. At times, anhydrous ammonia is employed for neutralizing the acid left on the seed. U.S. Pat. No. 4,064,636 is typical of the delinting apparatus which employs sulfuric acid and discloses the use of a surfactant with sulfuric acid, the surfactant being used as a wetting agent. Other patents disclosing the acid delinting of cottonseed are: U.S. Pat. Nos. 249,691, 310,628, 340,635, 344,651, 400,786, 307,100, 297,193, 13,708, 71,499, 299,378, and 695,305.
In U.S. Pat. No. 2,618,103, a process is disclosed in which the cottonseeds are prewet with water containing a "wetting agent" and dye, the wetting agent being used for better penetration of the water into the seed surfaces. Concentrated sulfuric acid is then added to the wetted seeds for delinting them.
The present invention reduces the amount of acid required for the delinting of the seeds, reduces to a minimum or eliminates wholly the use of external heat for carrying out chemical reaction; eliminates the necessity of using water as a pre-wetting agent on the seeds and reduces to a minimum the requirement for neutralizing the excess acid; facilitates the ready removal of the lint from the seed; provides a lint byproduct which is useful and speeds up the time required to remove the lint from the seeds.